hi, I can relate to your problem, my little boy is nearly 4 and thankfully, everything crossed has grown out of or been snapped out of this behaviour. he went through a period of doing similar things at pre school, it was embarrassing, upsetting, frustrating and everything else in between! he's a lovely little boy and the thought of other children and adults judging him on this behaviour was awful, I work with adults with challenging behaviour and found it particularly distressing to see my son displaying similar behaviours.
he would show shame and remorse when I talked to him about his behaviour at school but I found it hard because he was so young I think he had trouble connecting the 'telling off' to the behaviour, so actually in a twisted sort of way I was pleased when he displayed the same behaviours towards me when in trouble for something unrelated, it meant I had a chance to immediately reprimand him and issue a consequence he could fully understand the origin of!
it all came to a head during a fateful visit to a supermarket, I, like my boys dad and grandparents, aunties etc was guilty of spoiling him sometimes and have come to realise I am doing him no favours with this behaviour. anyway long story short he wanted a toy which I said he could have, he then wanted another toy which I said no to, he then proceeded to hit me with the original toy, I remove it from him and calmly told him no toys now for hitting, he lost it completely, hitting screaming kicking, behaviours I had never seen before and did not wish to again, I finished the shop with a red face and stares from everyone else, a woman actually came up and told me well done for being strong and all I could think was please go away before he hits you too! lol anyway once in the car I had a little cry to de-stress, once I had calmed a little and with my little one still very agitated, I explained to him 'mummy is crying because shes really sad about what happened today, and look, youre crying too, the way you behaved has made us both really upset' I didn't intend to upset him more or 'blame' him but I felt it was important he knew how his behaviour had made us both feel, I then explained that because he was spoilt (I didn't use these exact words) and because of the hitting kicking etc when we got home I was going to remove all his toys until he could show mummy he appreciated them and learnt that hitting and hurting anyone was wrong, he remained upset, I followed through and removed everything, he was obviously upset by this and I think shocked too, I didn't keep punishing him, I explained I still loved him and it was finished now and we would just concentrate on being really big grown ups and get his toys back from now on, over the next few weeks he earned a lot of toys back and actually played with them a lot more than when he had thousands in his room. touch wood he has not done this again and the only problems we have had at pre school have been normal, boys play fighting with something and one of them got hit a bit hard type of things which I can certainly live with. that's just my experience and I certainly don't claim to be an expert, but I do believe in children understanding when they have done wrong and that there are always consequences. I also found more supervised play dates with children his age helped, getting him playing with another child who doesn't always do what he wants, but in a much calmer environment than a pre school which I think can sometime over stimulate children of that age. we also did purpose trips to the supermarket to snap him out of expecting a toy every time (totally our doing) I would tell him all the way there no toy today remember, just looking, no toy, really drummed it into him, and to be fair to him he coped really well and accepted it!
I know its awful when your going through this and I thought it would never end with mine, but looking back now It doesn't seem half as bad as it did at the time, and it did end! I'm not saying he's perfect now, but I'm not holding my breath everytime I go to pick him up waiting to be pulled to the side! remember schools are trained in things like this and if you are concerned, request a meeting with his key worker, or equivalent, and discuss some strategies/possible trigger etc together and try and put on a united front.